Sounds like a boring story. /x/ may be interested.
Frequent Re-Infection and Temporary Treatment
Several antibiotics, such as erythromycin, spiramycin, kitasamycin, josamycin (macrolide antibiotics), oxytetracycline, doxycycline, enrofloxacin, florfenicol, lincomycin, and amoxicillin, have been used to treat the disease caused by L. garvieae in fish farms.
Most in vitro studies with herbal extractives were performed against L. garvieae with no strong antibacterial activity, but essential oils, especially those that contain thymol or carvacrol, are more effective.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8473265/